After a bunch of failed attempts with my ancient el cheapo scanner, I've decided to have a bunch of old medium format negatives (120/220) scanned professionally. I've all but decided on ScanCafe---haven't pulled the trigger yet. Great prices... $0.99 each for medium format negatives. But even better, they'll scan all 200 negatives, let me review them, and then I only have to pay for the ones I actually want---with the caveat that I have to buy at least half.
Interesting twist: they send the photos to a facility they've built in India. That's how they can get a technician to scan and personally inspect/retouch each negative at such low prices. Downside: looks like it might be around 8 weeks before I see my scans (and get back my originals). But, these negatives have been sitting around since 97 so it's not like I'm in a hurry.
I'll let you know how it goes. Have you used ScanCafe or any other professional negative/print scanning service?